我正在尝试使用新的android体系结构组件,但我一时糊涂了。
我创建了一个viewmodel类

public class BuyViewModel extends ViewModel {

private BuyRepository buyRepository;
private LiveData<Adverts> advertsLiveData;
private boolean isLoading;
private int currentPage;

@Inject
public BuyViewModel(BuyRepository buyRepository) {
    this.buyRepository = buyRepository;
}

public void init(int currentPage) {
    this.currentPage = currentPage;
    if (this.advertsLiveData != null) {
        return;
    }
    Timber.tag("logi").d("BuyViewModel > init -> ");
    advertsLiveData = buyRepository.getAdverts(currentPage);
}

public LiveData<Adverts> getAdvertsLiveData() {
    return advertsLiveData;
}
}

在我的生命周期标签中观察livedata
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    buyViewModel = ViewModelProviders.of(this, viewModelFactory).get(BuyViewModel.class);
    buyViewModel.init(1);
    buyViewModel.getAdvertsLiveData().observe(this, adverts -> {
        Timber.tag("logi").d("BuyFragment > onActivityCreated -> ");
        assert adverts != null;
        adapter.addMoreAdverts(adverts.getResults());
    });

    setupViews();
}

但是当我用另一个片段替换这个片段并切换回这个片段时,方法onChange被调用了两次,并在rvAdapter中添加了相同数据的两部分。

最佳答案

我解决了!!!!
在创建viewmodel类时,我将“this”第一个参数传递给方法
buyViewModel = ViewModelProviders.of(**this**, viewModelFactory).get(BuyViewModel.class);
但我需要传递“getActivity()”,代码看起来是这样的
buyViewModel = ViewModelProviders.of(**getActivity()**,viewModelFactory).get(BuyViewModel.class);

关于android - 为什么 fragment 重新创建时onChange()调用了两次,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/44863065/

10-09 10:18